The present invention relates to a one pick weft inserting method and a one pick weft inserting control system in a jet loom for maintaining one pick of inserted weft positively in a restartable state prior to start-up of the jet loom.
Sometimes, in the event a jet loom stops its operation due to defective weft inserting for example, one pick of weft is inserted into a warp shed in a stopped state of the loom prior to restarting of the operation of the loom, and thereafter the loom is started up.
Generally, when a defective weft is removed in a loom, the operation of which has been stopped due to defective weft inserting, for example, the position of a cloth fell changes by a distance corresponding to a woven in portion of the defective weft and this is unavoidable. Further, this positional change eventually causes a weaving bar because beating is performed at the time of reverse operation of the loom after removal of the defective weft. To prevent the formation of such weaving bar, a defective weft is removed and one pick of weft is inserted in advance.
Also, according to the above removal and one pick weft-insertion, the length of the inserted weft can be adjusted to a proper state, thus resulting in the fact that the first weft inserting step can be operated with certainty after start-up of the loom.
Such one pick weft inserting operation (hereinafter referred to simply as "one pick weft inserting") can be done manually. It is also known to perform this weft inserting operation automatically by controlling a main nozzle, a weft length measuring device disposed behind the main nozzle, and a sub nozzle disposed in front of the main nozzle. In this regard, reference is here made to, for example, Japanese Patent Laid-Open Nos. 55660/79, 197350/83 and 185843/85.
More particularly, while the operation of the loom is stopped, the main nozzle and the sub nozzle (both hereinafter be referred to as named a "weft inserting nozzle") are operated and one pick of weft is unwound from the weft length measuring device and inserted into a warp shed. Particularly, according to the technique disclosed in Japanese Patent Laid-Open No. 55660/79, one pick of inserted weft is sucked by a suction nozzle provided on the side opposite to the feed side and in this state a loom is started up.
In such conventional technique, one pick weft inserting itself is performed under a normal condition and a predetermined tension is applied to the inserted weft, so that when the loom assumes a state permitting the start-up occurs breaking, resulting in short pick. More particularly, after one pick weft inserting and until start-up of the loom it is necessary to continue the operation of the weft inserting nozzle and that of the suction nozzle and thereby continue to maintain the weft at a predetermined tension, so the exposure time to a fluid jet becomes too long and there occurs untwisting of the weft, thus resulting in the strength being deteriorated to an extreme degree.